Controllable 3D Porous Ni Current Collector Coupled with Surface Phosphorization Enhances Na Storage of Ni₃S₂ Nanosheet Arrays

Abstract 3D porous Ni is fabricated via an easily scalable electroless plating method using a dynamic template formed through in‐situ hydrogen bubbles. The pore size in the range of several micrometers is controllable through adjusting the Ni²⁺ depositing rate and hydrogen bubbles releasing rate. The Ni₃S₂ nanosheet arrays anode is then grown on the unique 3D porous Ni current collector followed by subsequent surface phosphorization. The tremendous interconnected pores and rich voids between the Ni₃S₂ nanosheet arrays cannot only provide rapid transferring channels for Na⁺, but also accommodate volumetric changes of the Ni₃S₂ electrode during cycling, guaranteeing the integrity of the active material. In addition, the surface phosphorized layer enhances the electronic conductivity through providing an electron transport highway along the 3D Ni₃S₂, NiP₂ layer, and 3D porous Ni current collector, and simultaneously stabilizes the electrode/electrolyte interphase as a protecting layer. Because of these merits, the phosphorized 3D porous Ni₃S₂ (3D P‐Ni₃S₂) electrode is capable of delivering an ultra‐stable capacity of 387.5 mAh g⁻¹ at 0.1 A g⁻¹, and a high capacity retention of 85.3% even at a high current density of 1.6 A g⁻¹.